Tech to allow async shader compilation, disabled

[mvaligursky]

Tech needed for using KHR_parallel_shader_compile for async shader compilation.

A shader can be assigned on a device with true parameter (defaults to false) to skip the rendering with this shader until it is compiled and linked. The test is done using non-blocking API.

device.setShader(shader, true);

This is currently not used (false is always passed), as the situation described here is still very relevant: https://github.com/mvaligursky/webgl-parallel_shader_compile

Tests using ShaderCompile engine example with more spheres (unique shaders)

Findings on MacOS 14.3.1 and Chrome 121:

• the extensions returns true in vast majority of cases, even when the shader is not ready, which block the rendering when the shader us used. The bahaviour is pretty much equivalent to not using the extension at all:

Findings on Windows 10, Chrome 121:

• the situation is somehow better. The extension correctly reports shader not being done compiling, so we can correctly skip rendering with it. But the browser is somehow blocked on its internal threads during the compilation, and so the application is still very much unresponsive during those times.